Global paleogeography since the late Paleozoic: integrating geological databases, plate tectonic models and reconstructions of past mantle flow

Abstract

This thesis comprises three studies exploring the connections between Earth’s surface paleoenvironments, paleoclimate, eustatic sea-level change and deep mantle processes by integrating geological observations with numerical Earth models over the last ~400 Myr. I obtained flexible time-dependent global paleogeographic reconstructions since the late Paleozoic by building on a set of published paleogeographic maps, and tested and revised them using paleoenvironmental information indicated by marine fossil collections from the Paleobiology Database. As a result, the consistency ratio between the paleogeography and the paleoenvironments is increased from an average of 75% to nearly full consistency. I analysed the latitudinal distribution patterns of a global-scale database of lithologic indicators of climate over the last ~400 Myr. The results suggest that the paleolatitudinal distributions of the lithologies have changed through deep time, notably a pronounced pole-ward shift in the distribution of coals in early Permian. The distribution of evaporites indicate a predominantly bimodal pattern, as opposed to previously proposed bimodal or unimodal patterns. The distribution of glacial deposits is consistent with previous interpretations of the main icehouse and greenhouse periods during the last ∼400 Myr. The comparison between flooding of continents, modelled dynamic topography and published eustatic curves in the late Paleozoic indicates that the first-order flooding history of North America correlates with eustasy. South American flooding history during the Carboniferous are at odds with estimates of eustasy and can be explained by dynamic topography. The reference districts used to reconstruct eustatic curves which are most affected by dynamic topography are those in South China and North America. Therefore, the interpretation of stratigraphic data gathered from these regions should be treated with caution when used to estimate global sea level variations.